Pipe straightening machine



U. WEGNER ETAL.

PIPE STRAIGHTENING MACHINE Sept. 18, 1962 2 Sheets-Sheet 1 Filed Dec. 2,1958 ion/EH: RS U70 was-MEX.

HHNS LINPEHWNN P 18, 1952 u. WEGNER ETAL. 3,054,438

PIPE STRAIGHTENING MACHINE Filed Dec. 2, 1958 2 Sheets-Sheet 2 iwawoksuPo WEGNEK. HH'NS LINyEMPrNN Patented Sept. 18, 1962 3,054,438 PIPESTRAIGHTENING NAC Udo Wegner, Heidelberg, and Hans Lindemann, B elefeld,Germany, assignors to Th. (Ialow & (30., Bielefeld, Germany, a firm ofGermany Filed Dec. 2, 1958, Ser. No. 777,708 Claims. (Cl. 153-32) Thepresent invention relates to a straightening machine, particularly forstraightening tubes and pipes which have a relatively large diameter ascompared with the wall thickness thereof.

Although the known straightening machines are well adapted forstraightening gas and boiler pipes or the like of the conventionalcommercial diameters, that is, pipes of a diameter of from 10 to 150 mm.with wall thicknesses of 1 to 8 mm. in accordance with the respectivediameter, it is found that pipes and tubes of a relatively largediameter of, for example, 500 mm. and a wall thickness of, for example,only 8 mm., are easily distorted by bulges at those points where thestraightening rollers are staggered relative to each other. Thisapplies, for example, to a machine of a design as disclosed by theGerman Patent No. 538,338. Even though such bulges are often notapparent to the eye, they are usually suflicient to increase or even tocause deformations of the pipe, for example, when such pipe is embeddedin the ground.

It is therefore an object of the present invention to provide a machinefor straightening pipes and tubes which have a relatively small wallthickness as compared to the large outer diameter thereof and whichinsures that the straightening operation will not result in anydeformations or bulges in the pipes.

Some of the known straightening machines including the machine disclosedin the above-mentioned German patent are provided with straighteningrollers which are staggered relative to each other along the peripheryof the workpiece as seen in the longitudinal direction thereof. Thesestraightening rollers are adjustably mounted in a revolving frame. Inanother type of such machines, as disclosed by the U. S. Patent No.2,411,395, the straightening rollers are mounted in a stationaryposition and adjustable within several planes extending transverse tothe axis of the pipe, and each of these planes contains an even numberof straightening rollers, namely four. Although there have also beenother straightening machines with a revolving frame and threestraightening rollers within one plane, they could only be used forstraightening pipes of a relatively small diameter and a great wallthickness since when used for straightening pipes of a relatively greatdiameter and small wall thickness, they produced bulges in the pipes.

The straightening machine according to the present invention is similarto some of the known machines, as described above, insofar as it alsocomprises a revolving frame in which hyperbolically shaped straighteningrollers are mounted which are adjustable about radial axes and arestaggered relative to each other in the axial direction of the pipe, andbetween which rollers the pipe is passed nonrotatably by means of feedand withdrawing rollers.

In comparison to these prior machines it is, however, an importantfeature of the present invention to arrange and adjust the straighteningrollers so that, when the machine is not in operation but at astandstill, any generatrix of the pipe wall extending parallel to theaxis of the pipe intersects the line of contact of at least onestraightening roller with the pipe wall.

A large number of tests carried out have shown that the tendency of thepipes to bulge locally will decrease considerably or be entirely avoidedif the straightening machine is designed according to the invention,namely, by providing in each of the planes as many straightening rollersas possible. It has further been found that even the ends of the pipeswill be straightened comparatively well since the individualstraightening units follow each other very closely. It is therefore theessential feature of the invention that for straightening pipes andtubes of a relatively large diameter in comparison to the small wallthickness thereof, the pipe to be straightened cannot change itscircular cross sectional shape at the points where it is acted upon bythe straightening rollers. The provision of several straighteningrollers surrounding a pipe within the same plane practically correspondsto an arrangement of circular disks within the pipe which wouldsimilarly increase the stability of the pipe against bulging. It wouldtherefore also be possible to provide the pipe to be straightened at theinside thereof with suitable disks or the like which are adjustable tothe respective diameter of the pipe and remain therein while the pipe isbeing passed through the straightening machine. However, such means forpreventing the bulging of the pipe during the straightening processrequire a considerably greater efiort and expenditure than the meansaccording to the present invention because of the difliculty involved insecuring the necessary parts at the inside of the pipe. It has furtherbeen found that, when providing a plurality of straightening rollerswithin each of several planes extending transverse to the axis of thepipe and spaced from each other, an uneven number of straighteningrollers should be provided within each of these planes. Furthermore, thesame number of straightening rollers should be provided within eachtransverse plane, and those in one plane should be staggered relative tothose in an adjacent plane.

These and further objects, features, and advantages of the presentinvention will become more apparent from the following detaileddescription thereof, particularly when read with reference to theaccompanying drawings, in which FIGURE 1 shows a longitudinal section ofa straightening machine according to the invention including feed andwithdrawing rollers and a revolving frame with adjustable straighteningrollers intermediate the former rollers;

FIGURE 2 shows an end view of the feed rollers of the machine accordingto FIGURE 1;

FIGURE 3 shows a cross section taken along line AA of FIGURE 1 of arevolving frame with five straightening rollers disposed within a planeextending vertically to the axis of rotation of the frame; while FIGURE4 shows a cross section similar to that according to FIGURE 3 butshowing a revolving frame with nine straightening rollers disposedWithin the same plane.

As shown in FIGURE 1 of the drawings, the known straightening machinesof the type as described above usually consisted of a revolving frame 4which was rotatably mounted in bearings 1 and 2 and driven by a gear 3or the like. This revolving frame 4 contained, for example, fivehyperbolically curved straightening rollers 6, 7, 8, 9, and 10 whichwere mounted so as to be adjustable about the radial axes 11, 12, 13,14, and 15, respectively. These axes 11 to 15 were therefore disposedwithin parallel planes which extend at equal or unequal distancees fromeach other in a direction vertical to the axis of rotation of frame 4.

If a pipe 16 was to be straightened, it was passed through frame 4 inthe direction as shown by the arrow 17. The feed rollers 18 and 19 thenfed pipe 16 forwardly and between straightening rollers 11 to 15, whilerollers 20 and 21 withdrew the pipe from the machine.

With an arrangement of the straightening rollers as above described, abulging of the pipe walls could not large outer diameter and arelatively small wall thickness. According to the present invention,however, as shown I particularly in'FIGURES 3 and 4, each of thestraightening rollers 6 to 10 as previously applied is now associatedwith additional straightening rollers 6 to 10in such a manner that allof the rollers which are disposed within the same plane surround thepipe 16 as completely as possible so that it is practically impossiblethat, while the pipe is being straightened, its circular cross-sectionalshape will become distorted. The number of straightening rollers to beapplied within each plane transverse to the axis of the pipe dependsupon the diameter of the pipe to be straightened. Thus, while with apipe 16 of a diameter as illustrated in FIGURE 3 five straighteningrollers will cover almost the entire peripheral surface of the pipe, apipe 16 of a larger diameter, as illustrated in FIGURE 4, will require,for example, nine straightening rollers within each plane.

The peripheral contour of the straightening rollers is preferablydesigned so that the latter will have a linear engagement with the pipeto be straightened. The particular manner of mounting and adjusting thestraightening rollers does not form a part of the subject matter of thepresent invention and different means may be used for that purpose.Thus, for example, each group of straightening rollers 6 to 10 may beadjusted by itself or all of them may be adjusted together to thedesired diameter, or each straightening roller may be made adjustableindividually.

perbolic surfaces and being rotatably mounted on said frame, said setsof straightening rollers being located in planes extending at anangle-to said axis, the straighten- The distinguishing characteristic ofthe invention thus 7 consists in mounting a plurality of straighteningrollers within a revolving frame so as to be disposed either within aplurality of parallel planes transverse to the axis of the pipe ortubeto be straightened or at any event within a plurality of parallel planesextending at an angle to the axis of the pipe, and so that each planetransverse or inclined to the axis of the pipe contains such a number ofstraightening rollers that, except for small spaces between the rollersin each plane to allow for their unrestricted movement, the entireperipheral surface of the pipe to be straightened will be enclosed byand in engagement with the straightening rollers. 'Expressed in different words, the straightening rollers are disposed along the pipe ortube to be straightened so that, when the machine is at a standstill,any generatrix of the pipe wall extending parallel to the axis of thepipe will intersect ing rollers of each set being'spaced about said axisand about the peripheral cylindrical surface of the pipe, eachstraightening roller having a line of engagement with the cylindricalperipheral surface of the. pipe, said rollers being'spaced about theperipheral surface of said pipe in such a manner that any plane throughsaid axis intersects the line of engagement of at least one roller ineach set.

2. In a machine for straightening cylindrical pipes, in combination,frame means; feeding means for feeding a cylindrical pipe having an axisthrough said frame means in direction of said axis; means for rotatingsaid frame means and said pipe relative to each'other about said axis;and a plurality of sets of straightening rollers having hyperbolicsurfaces and being rotatably mounted on said frame, said sets ofstraightening rollers being located in parallel planes extending at thesame angle to said axis, the straightening rollers of each set beingspaced about said axis and about the peripheral cylindrical surface ofthe pipe, each straightening roller having a line of engagement with thecylindrical peripheral surface of the pipe, said rollers being spacedabout the peripheral surface of said pipe in such a manner that anyplane through said axis intersects the line of engagement of at leastone roller in each set. V t

3. In a machine for straightening cylindrical pipes, in combination,frame means; feeding means for feedinga cylindrical pipe having an axisthrough said frame means in direction of said axis; means for rotatingsaid frame means and said pipe relative to each other about said axis;and a plurality of sets of straightening rollers having hyperbolicsurfaces and being rotatably mounted on said frame, said sets ofstraightening rollers being located in planes extending at an angle tosaid axis, the straightening rollers of each set being uniformly spacedabout said axis and about the peripheral cylindrical surface of thepipe, each straightening roller having a line of engagement with thecylindrical peripheral surface of the pipe, the straightening rollers ofeach set being staggered in circumferential direction relative to thestraightening rollers in the at least one line of engagement of astraightening roller. 7

cally around the pipe and thus form helical generatrixes along the Wallof the pipe, each of which has a width cor-' responding to the width ofthe individual straightening rollers.

Although our invention has been illustrated and described with referenceto the preferred embodiments tthereof, we wish to have it understoodthat it is in no way limited to the details of such embodiments, but iscapable of numerous modifications within the scope of the appendedclaims.

Having thus fully disclosed our invention, what we claim is:

1. In a'machine for straightening cylindrical pipes, in combination,frame means; feeding means for feeding a cylindrical pipe having an axisthrough said frame means. in direction of said axis; means for rotatingsaid frame means and said pipe relative to each other about said axis;and a plurality of sets of straightening rollers having hyadjacent setsof straightening rollers, said lines of engagement of said staggeredrollers in said sets forming interrupted helical lines on thecylindrical surface of the pipe, said rollers being spaced about theperipheral surface of said pipe in such a manner that any plane throughsaid axis intersects the line of engagement of at least one roller ineach set, the projections of said lines of said straightening rollersonto a plane perpendicular to said axis forming a complete circle sothat all lines on said cylindrical peripheral surface of the pipeextending parallel to said axis intersect with the line of engagement ofat least one straightening roller.

4. In a machine for' straightening cylindrical pipes, in combination,frame means; feeding means for feeding a cylindrical pipe having an axisthrough said frame means in direction of said axis; means for rotatingsaid frame means and said pipe relative to each other about said axis; aplurality of sets of straightening rollers having hyperbolic surfacesand being'rotatably mounted on said frame, said sets of straighteningrollers beinglocated on planes extending at an angle to'said axis,'eachset of straightening rollers having an uneven number of straighteningrollers spaced about said axis and about the peripheral cylindricalsurface of the. pipe, each straightening roller having a line ofengagement with the cylindrical peripheral surface of the pipe, saidrollers being spaced about the peripheral surface of said pipe in such amanner that any plane through said axis intersects the line ofengagement of at least one roller in each set, the projections of saidlines of engagement of said straightening rollers onto a planeperpendicular to said axis forming a complete circle so that all lineson said cylindrical peripheral surface of the pipe extending parallel tosaid axis intersect with the line of engagement of at least onestraightening roller.

5. In a machine for straightening cylindrical pipes, in combination,frame means; feeding means for feeding a cylindrical pipe having an axisthrough said frame means in direction of said axis; means for rotatingsaid frame means and said pipe relative to each other about said axis; aplurality of sets of straightening rollers having hyperbolic surfacesand being rotatably mounted on said frame, said sets of straighteningrollers being located in parallel planes extending at the same angle tosaid axis, each set of straightening rollers having an uneven number ofstraightening rollers uniformly spaced about said axis and about theperipheral cylindrical surface of the pipe, each straightening rollerhaving a line of engagement With the cylindrical peripheral surface ofthe pipe, said rollers being spaced about the perpheral surface of saidpipe in such a manner that any plane through said axis intersects theline of engagement of at least one roller in each set, the projectionsof said lines of engagement of each set of straightening rollers onto aplane perpendicular to said axis forming substantially a complete circleso that all lines on said cylindrical peripheral surface of the pipeextending parallel to said axis intersect With the line of engagement ofmore than one straightening roller.

6. In a machine for straightening cylindrical pipes, in combination,frame means; feeding means for feeding a cylindrical pipe having an axisthrough said frame means in direction of said axis; means for rotatingsaid frame means and said pipe relative to each other about said axis;and a plurality of sets of straightening rollers having hyperbolicsurfaces and being rotatably mounted on said frame means, said sets ofstraightening rollers being substantially located in planes extending atan angle to said axis, each set of straightening rollers having anuneven number of straightening rollers uniformly spaced about said axisand about the peripheral cylindrical surface of the pipe, eachstraightening roller having a line of engagement with the cylindricalperipheral surface of the pipe and said lines of engagement in each setof straightening rollers substantially enclosing the peripheral surfaceof the pipe, said rollers being spaced about the peripheral surface ofsaid pipe in such a manner that any plane through said axis intersectsthe line of engagement of at least one roller in each set, and thestraightening rollers of each set being staggered in circumferentialdirection relative to the straightening rollers in the adjacent sets ofstraightening rollers so that all lines on said cylindrical peripheralsurface of the pipe extending parallel to said axis intersect at anyinstant With the line of engagement of at least one straighteningroller.

7. In a machine for straightening cylindrical pipes, in combination,frame means; feeding means for feeding a cylindrical pipe having an axisthrough said frame means in direction of said axis; means for rotatingsaid frame means and said pipe relative to each other about said axis;and a plurality of sets of straightening rollers mounted spaced fromeach other in direction of said axis on said frame means, each of saidstraightening rollers being rotatably mounted on said frame means andhaving a hyperbolic surface having a line of engagement with theperipheral surface of said pipe, the straightening rollers in each setbeing spaced about the peripheral surface of the pipe so that any planethrough said axis intersects the line of engagement of at least oneroller in each set and the projections of said lines of engagement ofsaid straightening rollers onto a plane perpendicular to said axisforming a complete circle so that all lines on said cylindrical surfaceof the pipe extending parallel 6 to said axis intersect With the line ofengagement of at least one straightening roller.

8. In a machine for straightening cylindrical pipes, in combination,frame means; feeding means for feeding a cylindrical pipe having an axisthrough said frame means in direction of said axis; means for rotatingsaid frame means and said pipe relative to each other about said axis;and a plurality of sets of straightening rollers, each composed of anuneven number of rollers and mounted spaced from each other in directionof said axis, on said frame means, each of said straightening rollersbeing rotatably mounted on said frame means and having a hyperbolicsurface having a line of engagement with the peripheral surface of saidpipe, the straightening rollers in each set being spaced about theperipheral surface of the pipe so that any plane through said axisintersects the line of engagement of at least one roller in each set andthe projections of said lines of engagement of said straighteningrollers onto a plane perpendicular to said axis forming a completecircle so that all lines on said cylindrical surface of the pipeextending parallel to said axis intersect with the line of engagement ofat least one straightening roller.

9. In a machine for straightening cylindrical pipes, in combination,frame means; feeding means for feeding a cylindrical pipe having an axisthrough said frame means in direction of said axis; means for rotatingsaid frame means and said pipe relative to each other about said axis;and a plurality of straightening rollers mounted spaced from each otherin direction of said axis on said frame means, the rollers in each setof rollers being offset with respect to the rollers in the set adjacentthereto, each of said straightening rollers being rotatably mounted onsaid frame means and having a hyperbolic surface having a line ofengagement with the peripheral surface of said pipe, the straighteningrollers in each set being spaced about the peripheral surface of thepipe so that any plane through said axis intersects the line ofengagement of at least one roller in each set and the projections ofsaid lines of engagement of said straightening rollers onto a. planeperpendicular to said axis forming a complete circle so that all lineson said cylindrical surface of the pipe extending parallel to said axisintersect with the line of engagement of at least one straighteningroller.

10. In a machine for straightening cylindrical pipes, in combination,frame means; feeding means for feeding a cylindrical pipe having an axisthrough said frame means in direction of said axis; means for rotatingsaid frame means and said pipe relative to each other about said axis;and a plurality of sets of straightening rollers mounted spaced fromeach other in the direction of said axis and on said frame means, eachof said straightening rollers being rotatably mounted on said framemeans and having a hyperbolic surface having a line of engagement Withthe peripheral surface of said pipe, the straightening rollers in eachset being disposed about the peripheral surface of the pipe in a such amanner that any plane through said axis intersects the line ofengagement of at least one roller in each set.

References Cited in the file of this patent UNITED STATES PATENTS299,615 Borchardt June 3, 1884 456,883 Brightman July 28, 1891 613,754Brightman Nov. 8, 1898 1,326,981 Soderlund Jan. 6, 1920 1,859,851Stiefel May 24, 1932 FOREIGN PATENTS 452,124 Italy Oct. 10, 1949

